Thermic telephone-transmitter



PIETER DE LANGE AND ROBERT AERNOUT BARON VAN LYNDEN.

THERMIC TELEPHONE TRANSMITTER.

APPLICATION man 1 58.29, 1916. RENEWED JUNE 6,1921.

Patented Aug. 30, 1921.

Pieter Lang? UNITED STATES PATENT OFFICE.

-PIETER DE LAN GE AND ROBERT AERNOUT BARON VAN LYNDEN, OF UTRECHT, ,NETHERLANDS, ASSIGNORS, BY MESNE ASSIGNMENTS TO. ,AMERICAN THERMOPHOINE COMlANY, OF BOSTON, MASSACHUSETTS, A. CORPORATION OF MASSACHUSETTS.

THERMIG TELEPHONE-TRANSMITTER.

Specification of Letters Patent.

Application filed February 29, 1916, Serial No. 81,235. Renewed JunejG, 1921. Serial No. 475,554.

To aZZ whom it may concern;

Be it known that we, Pin'rnn on LANGE and ROBERT AnnNoU'r BARON VAN LYNDEN, both subjects of the Queen of the Netherlands, and residing at Utrecht, in the Netherlands, have invented new and useful Improvements in Thermic Telephone-Transmitters, (for which we have filed applications in Germany, Feb. 11, 1915, and in Great Britain, April 19, 1915, the latter having issued as Patent No. 5,837, April 19, 1916,) of which the following is a specification.

Our invention relates to improvements in thermic telephones, and its object is to provide a transmitting instrument which, as compared with the contact microphones hitherto in use, has the advantages of being able to stand greater quantities of energy, and of lasting for an almost unlimited time. Two constructions of the thermic transmitter are illustrated by way of example in I the accompanying drawing, Figures 1 and 2 showing the respective constructions in I vertical section.

The transmitter illustrated in Fig; 1 comprises two cup-like bodies 1 and 2 connected together to form a sounding box andsecured by screws 3 and 1 to a bolt 5. The bolt 5 also serves for securing the support 6 of the heating conductors 7, which may be of any suitable form and connected in any suitable manner. Between the support 6 and the inner wall of the cup-shaped bodies 1, 2, are arranged sleeves 8 and 9 respectively of insulating material, incasing the bolt 5. The free edges of the bodies 1 and 2 are arranged so as to leave an annular slot 10 between them. Through the said slot 10, and through openings 11 provided in the body 1, the sound can penetrate from the outside into the sounding box formed by the bodies 1 and 2, and act on the heating conductors '7 in said box. The heating conductors which may be in series, parallel or mixed connection, are connected to the current conductors or line wires 12, 13.

The manner in which our improved transmitter operates, that is to say, the theory of its operation, has not been determined with certainty as'yet. It seems probable however, that the alternate compressionandrarefaction of air taking place within the transmitter through the action of sound compression and rarefaction of air within the transmitter will produce variations in the temperature of the wires 7,'and it is well-known that the electrical resistance of a conductor will vary with its temperature.

Instead of a partly open sounding box as illustrated in Fig. 1, a closed casing might be provided for the heating conductors, and a portion of the wall of said casing might be in the form of a diaphragm for transmitting the sound. Such a construction might be as shown in Fig. 2, wherethe parts 2, 3,4, 5, 6, 7, 8, 9, 12, and l3'are exactly the same as in Fig. 1, but the member 1 of the casing or box is not spaced at the edge from the member or cup 2, neither is such member 1 perforated, but it is made to form a closed box with the member 2, and is made of flexible material to constitute a diaphragm which will vibrate in response to sound waves and thus admit or transmit such sound waves to the interior of the transmit ter box, so that they will impinge upon the heating conductors 7.

We claim:

1. The combination, in a thermic telephone transmitter, of a sounding box, heating conductors in said sounding box, a sup- Patented Aug. 30, 1921.

ing conductors in said sounding box, a support for said heating conductors in said sounding box, means for supplying current to said heating conductors and an annular slot in said sounding box for admitting sound into it.

i. The combination, in a thermic teiephone transmitter, of a sounding box, heating conductors in said sounding box, a support for said heating conductors, in said sounding box, means for supplying current to said heating conductors, and openings and an annular slot in said sounding box for admitting sound into it.

The combination, in a thermic telephone transmitter, of a sounding box, heat ing conductors in said sounding box, a support for said heating conductors in said sounding box, lineiwires for supplying current to said heating conductors, and means for admitting sound into said sounding box, said sounding box being formed oi two cup shaped bodies.

6. The combination, in a thermic telephone transmitter, of a sounding box, heating conductors in said sounding box, a support for said heating conductors in said sounding box, means for supplying current to said heating conductors, and means for admitting sound into said sounding box,

said sounding box being formed of two cupshaped bodies, means for securing together said cup-shaped bodies, said means being adapted to carry thesupport for said heating conductors.

ihe combination, in a thermic telephone transmitter, 01 a sounding box,heating conductors in said sounding box, a support for said heating conductors in said sounding box, means for supplying current to said heating conductors, and means for admitting sound into said sounding box, said sounding box being formed of two cupshaped bodies, a bolt for securing together said cup-shaped bodies, insulating sleeves on said bolt adapted to engage on either side the support for said heating conductors, and means for exerting axial pressure on said cup-shaped bodies, said insulating sleeves and said support.

8. A sound transmitter, comprising a box constructed to admit sound waves to its interior, a conductor located within said box and exposed to the impinging action of the sound waves, andadapted to have its resistance fluctuate as the sound waves impinge upon it, and line wires for supplying electric current to said conductor. 1

V 9. 1i thermic telephone transmitter comprising a casing permeable to sound waves, thermic conductors located in said casing and exposed and responsive to said sound waves for altering the current flow therein, and means for connecting said vconduetors with an electric line circuit.

In testimony whereof we have signed this specification.

f METER de LANCE.

ROBERT AERNOUT BARON van ,LYNDEN. V 

